// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

use crate::data::{contains_nulls, ArrayData};

use arrow_buffer::bit_chunk_iterator::BitChunks;

use arrow_schema::DataType;

// whether bits along the positions are equal

// `lhs_start`, `rhs_start` and `len` are _measured in bits_.

#[inline]

pub(super) fn equal_bits(

    lhs_values: &[u8],

    rhs_values: &[u8],

    lhs_start: usize,

    rhs_start: usize,

    len: usize,

) -> bool {

    let lhs = BitChunks::new(lhs_values, lhs_start, len).iter_padded();

    let rhs = BitChunks::new(rhs_values, rhs_start, len).iter_padded();

    lhs.zip(rhs).all(|(a, b)| a == b)

}

#[inline]

pub(super) fn equal_nulls(

    lhs: &ArrayData,

    rhs: &ArrayData,

    lhs_start: usize,

    rhs_start: usize,

    len: usize,

) -> bool {

    match (lhs.nulls(), rhs.nulls()) {

        (Some(lhs), Some(rhs)) => equal_bits(

            lhs.validity(),

            rhs.validity(),

            lhs.offset() + lhs_start,

            rhs.offset() + rhs_start,

            len,

        ),

        (Some(lhs), None) => !contains_nulls(Some(lhs), lhs_start, len),

        (None, Some(rhs)) => !contains_nulls(Some(rhs), rhs_start, len),

        (None, None) => true,

    }

}

#[inline]

pub(super) fn base_equal(lhs: &ArrayData, rhs: &ArrayData) -> bool {

    let equal_type = match (lhs.data_type(), rhs.data_type()) {

        (DataType::Union(l_fields, l_mode), DataType::Union(r_fields, r_mode)) => {

            l_fields == r_fields && l_mode == r_mode

        }

        (DataType::Map(l_field, l_sorted), DataType::Map(r_field, r_sorted)) => {

            let field_equal = match (l_field.data_type(), r_field.data_type()) {

                (DataType::Struct(l_fields), DataType::Struct(r_fields))

                    if l_fields.len() == 2 && r_fields.len() == 2 =>

                {

                    let l_key_field = &l_fields[0];

                    let r_key_field = &r_fields[0];

                    let l_value_field = &l_fields[1];

                    let r_value_field = &r_fields[1];

                    // We don't enforce the equality of field names

                    let data_type_equal = l_key_field.data_type() == r_key_field.data_type()

                        && l_value_field.data_type() == r_value_field.data_type();

                    let nullability_equal = l_key_field.is_nullable() == r_key_field.is_nullable()

                        && l_value_field.is_nullable() == r_value_field.is_nullable();

                    let metadata_equal = l_key_field.metadata() == r_key_field.metadata()

                        && l_value_field.metadata() == r_value_field.metadata();

                    data_type_equal && nullability_equal && metadata_equal

                }

                _ => panic!("Map type should have 2 fields Struct in its field"),

            };

            field_equal && l_sorted == r_sorted

        }

        (l_data_type, r_data_type) => l_data_type == r_data_type,

    };

    equal_type && lhs.len() == rhs.len()

}

// whether the two memory regions are equal

#[inline]

pub(super) fn equal_len(

    lhs_values: &[u8],

    rhs_values: &[u8],

    lhs_start: usize,

    rhs_start: usize,

    len: usize,

) -> bool {

    lhs_values[lhs_start..(lhs_start + len)] == rhs_values[rhs_start..(rhs_start + len)]

}